Hydrodynamic bearing system and method for operating said hydrodynamic bearing system

ABSTRACT

Systems and methods related to hydrodynamic bearings are provided. One example hydrodynamic bearing system includes a sleeve assembly including a cross-member fluidically dividing a first interior cavity from a second interior cavity, a first shaft positioned in the first interior cavity, and a second shaft positioned in the second interior cavity. The hydrodynamic bearing system further includes a first journal bearing including a first fluid interface surrounding at least a portion of the first cantilever shaft and configured to support radial loads and a second journal bearing including a second fluid interface surrounding at least a portion of the second cantilever shaft and configured to support radial loads.

TECHNICAL FIELD

Embodiments of the subject matter disclosed herein relate tohydrodynamic bearing systems and methods for operating hydrodynamicbearing systems.

BACKGROUND

Hydrodynamic bearings are used in various operating environments due totheir increased longevity and ability to more effectively manage thermalloads, relative to ball bearings or roller bearings. One such operatingenvironment is the use of hydrodynamic bearings in x-ray tubes of x-rayimaging systems or computed tomography (CT) imaging systems. Certainx-ray tubes, for example, utilize hydrodynamic bearings owing at leastin part to their thermodynamic characteristics and durability. However,certain hydrodynamic bearings may experience leaks due to the bearing'sboundary conditions and/or may not achieve a desired load carryingcapacity. Hydrodynamic bearings may also be known as liquid metalbearings or spiral groove bearings.

SUMMARY

In one embodiment, a hydrodynamic bearing system is provided. Thehydrodynamic bearing system comprises a sleeve assembly including across-member fluidically dividing a first interior cavity from a secondinterior cavity. The hydrodynamic bearing system further includes afirst shaft positioned in the first interior cavity and a second shaftpositioned in the second interior cavity. The hydrodynamic bearingsystem also includes a first journal bearing having a first fluidinterface surrounding at least a portion of the first shaft andconfigured to support radial loads and a second journal bearing having asecond fluid interface surrounding at least a portion of the secondshaft and configured to support radial loads.

The above advantages and other advantages, and features of the presentdescription will be readily apparent from the following DetailedDescription when taken alone or in connection with the accompanyingdrawings. It should be understood that the summary above is provided tointroduce in simplified form a selection of concepts that are furtherdescribed in the detailed description. It is not meant to identify keyor essential features of the claimed subject matter, the scope of whichis defined uniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be better understood from reading thefollowing description of non-limiting embodiments, with reference to theattached drawings, wherein below:

FIG. 1 is a block schematic diagram of an exemplary x-ray imagingsystem, according to an embodiment.

FIG. 2 is a pictorial view of a portion of an x-ray source including ahydrodynamic bearing system, according to an embodiment.

FIG. 3 is a first exemplary hydrodynamic bearing assembly, according toan embodiment.

FIG. 4 is a second exemplary hydrodynamic bearing assembly, according toan embodiment.

FIG. 5 is an exemplary method for operation of a hydrodynamic bearingsystem, according to an embodiment.

DETAILED DESCRIPTION

The following description relates to various embodiments of hydrodynamicbearing systems. The hydrodynamic bearing systems are designed to fixaxial fluid boundary conditions at selected ends of discrete shaftsenclosed by different sections of a sleeve. Increased bearing stabilityand working fluid (e.g., liquid metal) control and a subsequent bearingleak reduction result from the fixed axial fluid boundary conditions.Thus, the bearing leaks may be reduced across different stages of thesystem (e.g., handling, processing, and operation). To achieve the fixedboundary conditions the sleeve includes a cross-member dividing thesleeve into the two distinct cavities. Further, in certain systemembodiments, the shafts are cantilever shafts supported at one end by,for example, a housing of the system. In this way, the structuralsupport of straddle type bearings can be achieved while reducing thehydrodynamic drawbacks of previous straddle bearing designs, therebyexpanding the applicability of the bearing system. As such, in oneuse-case example, the bearing system may be deployed in computedtomography (CT) imaging systems having higher gantry loads in comparisonto CT imaging systems with x-ray sources supporting a fixed bearingshaft on only one axial end. Providing two cantilever shafts alsodecreases focal spot motion in x-ray sources employing the bearingsystem in relation to systems using one cantilever shaft. In additionalexamples, the cross-member may be designed with a targeted amount ofcompliance to reduce sleeve-shaft misalignment. As a result, thethickness of the fluid interface in the bearing may be reduced, ifdesired, thereby increasing the bearing's load carrying capacity andefficiency.

An x-ray imaging system including an x-ray source and x-ray controlleris shown in FIG. 1. An example of an x-ray imaging system is shown inFIG. 2 with a hydrodynamic bearing assembly enabling anode rotation.FIG. 3 shows a first embodiment of a hydrodynamic bearing system. FIG. 4shows a second embodiment of a hydrodynamic bearing system with aflexible cross-member enabling sleeve-shaft misalignment to be reduced.FIG. 5 shows a method for operation of a hydrodynamic bearing system.

FIG. 1 illustrates an x-ray imaging system 100 designed to generatex-rays. The x-ray imaging system 100 is configured as an imaging system(e.g., CT imaging system, radiography imaging system, fluoroscopyimaging system, tomography imaging system, etc.) in FIG. 1. However, thex-ray imaging system 100 has applicability to fields beyond imaging,medical devices, and the like. For instance, the x-ray imaging system100 may be deployed in crystallography systems, security scanners, x-rayphotography systems, etc. It will also be appreciated that thehydrodynamic bearing systems described in greater detail herein may bedeployed in alternate types of systems utilizing hydrodynamic bearings,in some instances. Hydrodynamic bearing systems may also be known asliquid metal bearing systems or spiral groove bearing systems, etc.

In the imaging system example, the imaging system may be configured toimage a subject 102 such as a patient, an inanimate object, one or moremanufactured parts, and/or foreign objects such as dental implants,stents, and/or contrast agents present within the body.

The x-ray imaging system 100 may include at least one x-ray source 104configured to project a beam of x-ray radiation 106. Specifically, inthe illustrated embodiment, the x-ray source 104 is configured toproject x-ray radiation beams 106 towards a detector array 108 andthrough the subject 102. In some system configurations, the x-ray source104 may project a cone-shaped x-ray radiation beam which is collimatedto lie within an X-Y-Z plane of a Cartesian coordinate system. However,other beam profiles and/or systems omitting the detector array have beenenvisioned. Each detector element of the array produces a separateelectrical signal that is a measurement of the x-ray beam attenuation atthe detector location.

Although FIG. 1 depicts only a single x-ray source 104 and detectorarray 108, in certain embodiments, multiple x-ray sources and/ordetectors may be employed to project a plurality of x-ray radiationbeams and detect said beams. For instance, in the CT imaging systemuse-case example, multiple detectors may be used in tandem with multiplex-ray sources to acquire projection data at different energy levelscorresponding to the subject.

The x-ray imaging system 100 may further include an x-ray controller 110configured to provide power and timing signals to the x-ray source 104.It will be understood that that system may also include a dataacquisition system configured to sample analog data received from thedetector elements and convert the analog data to digital signals forsubsequent processing.

In certain embodiments, the x-ray imaging system 100 may further includea computing device 112 having a processor 114 and controlling systemoperations based on operator input. The computing device 112 receivesthe operator input, for example, including commands and/or scanningparameters via an operator console 116 operatively coupled to thecomputing device 112. The operator console 116 may include a keyboard, atouchscreen, and/or other suitable input device allowing the operator tospecify the commands and/or scanning parameters.

Although FIG. 1 illustrates only one operator console 116, more than oneoperator console may be included in the x-ray imaging system 100, forexample, for inputting or outputting system parameters, requestingexaminations, plotting data, and/or viewing images. Further, in certainembodiments, the x-ray imaging system 100 may be coupled to multipledisplays, printers, workstations, and/or similar devices located eitherlocally or remotely, for example, and connected via wired and/orwireless networks.

In one example, the computing device 112 stores the data in a storagedevice or mass storage 118. The storage device 118, for example, mayinclude a hard disk drive, a floppy disk drive, a compactdisk-read/write (CD-R/W) drive, a Digital Versatile Disc (DVD) drive, aflash drive, and/or a solid-state storage drive.

Additionally, the computing device 112 provides commands to the x-raycontroller 110 and other system components for controlling systemoperations such as x-ray beam formation, data acquisition and/orprocessing, etc. Thus, in certain embodiments, the computing device 112controls system operations based on operator input. To elaborate, thecomputing device 112 may use the operator-supplied and/or system-definedcommands and parameters to operate an x-ray controller 110, which inturn, may control the x-ray source 104. In this way, the intensity andtiming of x-ray beam generation may be controlled. It will also beunderstood that the rotational speed of a sleeve in the x-ray source maybe adjusted by the computing device 112 in conjunction with the x-raycontroller 110. The rotational speed adjustment of the sleeve may inducethe flow of liquid metal into a bearing interface in the x-ray source104, as described in greater detail herein.

The various methods and processes (such as the method described belowwith reference to FIG. 5) described further herein may be stored asexecutable instructions in non-transitory memory on a computing device(or controller) in x-ray imaging system 100. In one embodiment, thex-ray controller may include the executable instructions innon-transitory memory, and may apply the methods described herein tocontrol the x-ray source. In another embodiment, computing device 112may include the instructions in non-transitory memory, and may relaycommands, at least in part, to the x-ray controller which in turnadjusts the x-ray source output.

In one embodiment, a display 120 may also be in electronic communicationwith the computing device 112 and is configured to display graphicalinterfaces indicating system parameters, control setting, imaging data,etc.

FIG. 2 shows a detailed embodiment of a portion of an x-ray source, suchas an x-ray tube 200. The x-ray source 200 shown in FIG. 2 serves as anexample of the x-ray source 104 depicted in FIG. 1. As such, the x-raysource 200, shown in FIG. 2, as well as the other x-ray imaging systemembodiments described herein may include functional and/or structuralfeatures from the x-ray source 104, shown in FIG. 1, or vice versa.Furthermore, alternate embodiments combining features from one or moreof the systems have also been envisioned.

A rotational axis 250 along with a radial axis 252 are provided in FIG.2 as well as FIGS. 3-4 for reference. It will be understood that aradial axis is any axis perpendicular to the rotational axis 250.

The x-ray source 200 includes a housing 202 having a low-pressureenclosure 204 (e.g., vacuum enclosure) formed therein. It will beunderstood that a low-pressure enclosure infers a comparativelylow-pressure relative to atmospheric pressure. As such, the pressure inthe enclosure may be less than atmospheric.

The x-ray source 200 includes a hydrodynamic bearing system 205 with asleeve assembly 206 and a shaft assembly 208. In the illustratedexample, the sleeve assembly 206 is a rotational component and the shaftassembly 208 is a stationary component. However, embodiments in whichthe sleeve assembly is a stationary component and the shaft assembly isa rotational component, have been contemplated. In such an example, ananode 210 may be coupled to the shaft assembly 208 as opposed to thesleeve assembly 206. Nevertheless, in the illustrated embodiment, theanode 210 is coupled to the sleeve assembly 206. It will be understoodthat the motion denoted by the descriptors stationary and rotationaldenote the relative motion between the components. However, in certainuse-case examples, the x-ray tube may be integrated into a movingstructure. For instance, in the CT imaging system use-case, the x-raytube may be integrated into a rotating gantry. As such, in smaller scaleframe of reference, the shaft is stationary relative to the sleeve butin a larger scale frame of reference, both components exhibit similarrotational motion in the gantry. However, in alternate use-casescenarios, the x-ray tube may be integrated into a stationary structurein regard to the larger scale frame of reference.

The sleeve assembly 206 includes a sleeve body 212 and a cross-member214 partitioning an interior of the body into a first interior cavity216 and a second interior cavity 218. Thus, the cross-member 214fluidically divides interior sleeve cavities. The shaft assembly 208includes a first shaft 220 residing in the first interior cavity 216 anda second shaft 222 residing in the second interior cavity 218. The firstshaft 220 is shown fixedly coupled to the housing 202 at a first axialend 224 and unsupported at the opposing axial end. However, the firstshaft 220 may be fixedly attached to another suitable stationary x-raysource component, in other examples. Although certain structural detailsof the second shaft 222 are obscured from view in FIG. 2, it will beappreciated that one axial end of the second shaft 222 may be coupled tothe housing 202 or other suitable stationary component in the x-raysource. Thus, the bearing system may be formed as a straddle bearingsystem. Further, in other embodiments in which the shaft assemblyrotates, the sleeve assembly may include two sleeve sections fixedlyattached to the housing at an axial end of each section. The structuralfeatures of the sleeve and shaft assemblies are elaborated upon ingreater detail herein with regard to the embodiments shown in FIGS. 3-4.

The cross-member 214 in the sleeve assembly 206 enables fluid boundaryconditions on axial ends of each of the first and second shaft 220 and222 to be fixed. Fixing the fluid boundary conditions at the axial endsof the shafts allows the stability and control of the fluid in therotational interfaces in the hydrodynamic bearing system 205 to beincreased in relation to systems using a single continuous shaft with aseries of hydrodynamic bearings in fluidic communication with oneanother. Consequently, the likelihood of leaks from the hydrodynamicbearing system is reduced.

It will also be understood that the leak reductions may be achievedwhile jointly increasing load carrying capacity of the assembly via thecantilever attachment of both shafts. Providing two shafts in the shaftassembly 208 fixedly supported at one end, decreases unwanted motion ofa focal spot 226 on the anode 210 during operation due to the increasedbearing support in comparison to systems using a single cantilevershaft.

The structural and functional details of the cross-member 214 areexpanded upon in greater detail herein with regard to the hydrodynamicbearing system embodiments illustrated in FIGS. 3-4. The sleeve assembly206 includes structures designed fix the boundary conditions on axialends of discrete shafts in the system while also fixedly attachingopposing axial ends of the shafts to stationary components in thesystem. Fixing the boundary conditions at ends of discrete shafts allowsthe liquid metal, or other suitable working fluid, to be stabilized suchthat leaks from the seals in the system are significantly reduced, inrelation to systems using a series of hydrodynamic bearings in fluidiccommunication with one another.

The hydrodynamic bearing system 205 includes a plurality of hydrodynamicbearings including a journal bearing 228 and a thrust bearing 230. Thesystem may however include additional bearings obscured from view inFIG. 2. For instance, in the embodiments shown in FIGS. 3-4, the systemincludes two journal bearings and two thrust bearing. Still further inother embodiments, the bearing system may include an alternate numberand/or types of bearings. For instance, the system may include twojournal bearing and one thrust bearing in one example, or more than twojournal bearings and two thrust bearings, in other examples. Thehydrodynamic journal bearing 228 is designed to support radial loads andhydrodynamic thrust bearing 230 is designed to support axial loads. Inthis way, loads on the sleeve are managed to enable efficient sleeverotation.

Each of the bearings include an interface 232 in which a working fluid(e.g., liquid metal) serving as a lubricant and supporting loads isprovided. The thickness of the interface may be selected based onfactors such as the type liquid metal or other working fluid used in thebearing, manufacturing tolerances of the components, expected systemoperating temperature, etc. Thus, in one use-case example, the liquidmetal interface may be on the order of 5 microns (μm)-40 μm. In oneexample, the liquid metal used as the working fluid in the bearingassembly may include gallium, tin, indium, combinations thereof, etc.However, working fluid other than liquid metal have been envisioned suchgrease, oil, combinations thereof, etc.

In the illustrated embodiment, the anode 210 is coupled to the sleeveassembly 206. However, as previously mentioned, embodiments with theanode coupled to rotational shaft assemblies have been envisioned. Theanode 210 includes the focal spot 226 serving as a surface receiving abeam of electrons from a cathode 234, during x-ray source 200 operation.

The cathode 234 may receive signals from a controller, such as the x-raycontroller 110 shown in FIG. 1, to generate an electron beam directedtoward a surface of the anode 210. An x-ray beam 236 is generated whenthe electron beam from the cathode 234 strikes the focal spot 226 of theanode 210. The x-rays are emitted through an x-ray window 238 in thehousing 202.

A rotor 240 and a stator 242 are also provided in the x-ray source 200.The rotor 240 is coupled to the sleeve assembly 206, in the illustratedembodiment, and is designed to impart rotational motion thereto.However, in embodiments where the shaft assembly rotates the rotor maybe coupled to the first and second shafts in the shaft assembly. Thestator 242 is shown positioned external to the low-pressure enclosure204. However, other suitable stator locations have been envisioned.Typically, the rotor and stator can include windings, magnets,electrical connections, etc., electromagnetically interacting togenerate rotor rotation responsive receiving control commands, from forexample, the x-ray controller 110, shown in FIG. 1.

Various embodiments of the hydrodynamic bearing system designed toreduce leaks from bearings in the system, are described in greaterdetail herein with regard to FIGS. 3-4. The embodiments of thehydrodynamic bearing systems depicted in FIGS. 3-4 are examples of thehydrodynamic bearing system 205, shown in FIG. 2. As such, structuraland/or functional features from the bearing systems shown in FIGS. 3-4may be included in the bearing system 205, shown in FIG. 2, in othercontemplated embodiments.

FIG. 3 shows an example of a hydrodynamic bearing system 300. Thehydrodynamic bearing system 300 includes a shaft assembly 302 and asleeve assembly 304. It will be understood that in one example, ananode, such as the anode 210, shown in FIG. 2, may be attached to thesleeve assembly 304. Thus, during system use, the sleeve assemblyrotates while the shaft assembly remains relatively stationary. However,as previously mentioned, embodiments where the sleeve assembly is keptstationary and the shaft assembly rotates, have been envisioned.

The sleeve assembly 304 includes a first interior cavity 306 and asecond interior cavity 308 formed in a sleeve body 310. The sleeve body310 is shown as a monolithic structure. However, sleeves with differentsections connected to one another may be used, in other embodiments. Forinstance, in other embodiments, the sleeve body may manufactured indifferent sections and the sections may be coupled via mechanicalattachment (e.g., bolting), welding, press-fitting, shrink-fitting,combinations thereof, etc.

The sleeve assembly 304 further includes a cross-member 312 radiallyextending across an interior of the sleeve body 310. To elaborate, thecross-member 312 fluidly divides the first and second interior cavities306, 308 in the sleeve assembly 304. The cross-member 312 thereforeincludes a first surface 314 forming a section of the boundary of thefirst interior cavity 306 and a second surface 316 forming a section ofthe boundary of the second interior cavity 308. Thus, the first interiorcavity 306 and the second interior cavity 308 are conceptually formed asblind openings. A variety of cross-member constructions have beencontemplated such as a construction where the cross-member is a pluginserted into the sleeve assembly. In such an example, the plug may becoupled to the sleeve body via press-fitting, welding, mechanicalattachment, combinations thereof, etc. and/or may be formed as acylinder. In other examples, the body and the cross-member of the sleeveassembly may be jointly formed via suitable manufacturing techniquessuch as machining, casting, etc. It will therefore be understood thatthe sleeve body 310 and the cross-member 312 may be formed from asimilar material, in some examples, or out of different materials, inother examples. Suitable materials for the sleeve assembly 304 and/orshaft assembly 302 may include metallic materials, ceramic materials,combinations thereof, etc.

The cross-member 312 allows the fluid boundary conditions of the bearinginterfaces, discussed in greater detail herein, to be fixed, increasingstability of fluid (e.g., liquid metal) capillary forces and pressure.Fluid leaks through seals 356 and 360 in the system can therefore besignificantly reduced due to the relatively large reduction in fluidmotion.

The shaft assembly 302 includes a first shaft 318 and second shaft 320.The first shaft 318 is fixedly coupled at one axial end 322 to asuitable system component such as the housing 202, shown in FIG. 2.Likewise, the second shaft 320 is fixedly coupled at one axial end 324to a suitable system component (e.g., the housing 202 shown in FIG. 2).Thus, in the embodiment shown in FIG. 3, the first and second shafts 318and 320 are formed as cantilever shafts. However, as previouslymentioned, the sleeve may be fixedly attached to the housing at opposingaxial ends in embodiments where the shaft assembly rotates and thesleeve assembly remains substantially stationary during system use.

The hydrodynamic bearing system 205 includes a plurality of bearingsincluding fluid interfaces 326 (e.g., liquid metal interfaces) betweenouter surfaces 328 of the first and second shafts 318 and 320 andinterior surfaces 330 of the sleeve assembly 304. To elaborate, thesystem includes a first journal bearing 332, a second journal bearing334, a first thrust bearing 336, and a second thrust bearing 338, in theillustrated embodiment. However, other bearing arrangements have beenenvisioned such as bearing arrangements including two journal bearingand one thrust bearing, in one example, or a bearing arrangementincluding more than two journal bearing and/or more than two thrustbearings, in other examples. The journal bearings support radial loadsand the thrust bearings support axial loads. Each of the bearingsincludes a fluidic interface (e.g., liquid metal interface) between asection of a shaft included in the shaft assembly 302 and the sleevebody 310. Thus, each of the bearings include a fluid interfacecircumferentially surrounding the corresponding shaft. The first journalbearing 332 includes a first fluid interface 370, the second journalbearing 334 includes a second fluid interface 372, the first thrustbearing 336 includes a third fluid interface 374, and the second thrustbearing 338 includes a fourth fluid interface 376.

The first shaft 318 and the second shaft 320 are shown with herringbonegrooves 340 associated with the first journal bearing 332 and the secondjournal bearing 334, respectively. The sleeve assembly 304 maycorrespondingly include spiral grooves associated with the first andsecond journal bearings 332, 334. These grooves (herringbone and spiralgrooves) may work in conjunction to generate pressure in the workingfluid (e.g., liquid metal) to support the bearing load. It willtherefore be understood that the bearings described herein may beself-acting bearings designed to generate pressure using the surfacegeometries at the bearing interface. However, bearing embodimentsincluding alternate groove patterns or embodiments omitting at least aportion of the grooves to alter the bearing's flow dynamics, have beencontemplated.

The first thrust bearing 336 includes a flange 342 radially extendingfrom a body 344 of the first shaft 318 toward a complimentary section346 in the sleeve body 310. The second thrust bearing 338correspondingly includes a flange 348 radially protruding from thesecond shaft 320 into a complimentary section 350 in the sleeve body310. The flanges 342, 348 have radial ends 352 and axial sides 354 whichmay form an annular shape, in some cases.

The hydrodynamic bearing system 300 may further include seals designedto reduce the amount of fluid leaking from the bearings. The seals maybe rotating labyrinth seals providing a circuitous path impeding liquidmetal flow in axial directions away from the cross-member 312. However,additional or alternate types of suitable seals or combinations of sealshave been contemplated such as capillary seals, hydrodynamic seals,flange seals, foil seals, etc. The first seal 356 is shown positionedaxially outward (indicated via arrow 358) from the first journal bearing332. The second seal 360 is shown positioned axially outward (indicatedvia arrow 362) from the second journal bearing 334. The first seal 356and the second seal 360 are also shown positioned radially outward fromthe first journal bearing 332 and the second journal bearing 334,respectively. However, an alternate number of seals and/or sealarrangement may be used, in other embodiments. The first and secondthrust bearings 336 and 338 are shown positioned axially between thefirst and second journal bearings 332 and 334 and the first and secondseals 356 and 360. However, in other examples, the first and/or secondthrust bearings may be positioned adjacent to the unsupported axial endsof the first and second shafts 318 and 320. In such an example, thethrust bearing may be arranged with axially spacing between theunsupported shaft end and the cross-member to allow for thermal growthbetween the sleeve and the shaft. In this way, the likelihood of bearingwear caused by thermal expansion of system components can be reduced.

FIG. 4 shows another embodiment of a bearing system 400. The bearingsystem 400 again includes a sleeve assembly 402 and a shaft assembly404. The shaft assembly 404 again includes a first shaft 406 and asecond shaft 408 fixedly attached to a system component, such as thehousing 202 shown in FIG. 2, at axial ends of the respective shafts. Thehydrodynamic bearing system again includes a first journal bearing 410,a second journal bearing 412, a first thrust bearing 414, and a secondthrust bearing 416. A first seal 418 and a second seal 420 are alsoshown included in the hydrodynamic bearing system 400. The shafts,bearing, and seals may have functional and/or structural similaritieswith the shafts, bearings, and/or seals previously described with regardto FIG. 3. As such, redundant description is omitted for brevity.

The sleeve assembly 400 shown in FIG. 4 includes a cross-member 422 withfluidic isolation extensions 424 (e.g., plugs, caps, etc.) and aflexible component 426. Thus, the extensions 424 seal the interiorsleeve cavities. It will be understood that the flexible component hasgreater compliance than the sleeve sections 432 and 434. The fluidicisolation extensions 424 again fluidly divide the first interior cavity428 and the second interior cavity 430. The extensions 424 may bewelded, press-fit, mechanically coupled, etc., to the sections of thesleeve. It will be understood, that when the extensions are welded orpress-fit to the sleeve a welded interface and friction interface,respectively, will be formed.

The flexible component 426 is positioned axially between the fluidicisolation extensions 424 as well as a first section 432 and a secondsection 434 of a sleeve body 436. The flexible component 426 alsoradially spans an interior diameter of an anode 438. However, otherflexible component profiles have been envisioned and may be selectedbased on end-use design objectives. Additionally, the first section 432of the sleeve body 436 and the second section 434 of the sleeve body areshown attached to the anode 438 axially extending across an outercircumference of the cross-member 422. However, alternate sleeve sectionarrangements may be utilized in other embodiments. For instance, inanother example, a third sleeve body section may extend between thefirst section 432 and the second section 434 of the sleeve body 436 andcircumferentially enclose the flexible component 426. Continuing withsuch an example, the anode 438 may be coupled to an outer surface of thethird sleeve body section. The configuration and layout of the sleevebody sections may be selected based on packaging constraints, desiredflexion characteristics, etc.

The flexible component 426 is configured as a compliant memberaccommodating for flexion between the first section 432 and the secondsection 434 of the sleeve body 436. Thus, the flexible component 426 mayhave less bending stiffness than the first sleeve section 432 and thesecond sleeve section 434. Further, in one example, the flexiblecomponent may be less compliant under torsional loads than bendingloads. In this way, the flexible component may be relativelyrotationally stiff but selectively compliant under bending loads. Toelaborate, the flexible component 426 in the cross-member 422conceptually functions as a gimbal without having the mechanicalgyroscopic mechanisms. The use of the flexible component in thecross-member consequently decreases sleeve-shaft misalignment. Thedecreased sleeve-shaft misalignment allows the thickness of the fluidinterfaces in the first and second journal bearings 410 and 412 to bereduced, increasing the load carry capacity of the bearings and bearingefficiency, if wanted. Consequently, the sleeve can achieve increasedrotational speeds, if desired, during use of the x-ray source, therebyincreasing the applicability of the bearing system. As such, in the CTimaging system use-case, higher rotational speed of the gantry of the CTimaging system can be realized, if desired.

The compliance of the flexible component 426 in the cross-member 422 maybe achieved by adjusting the geometry and/or material of the flexiblecomponent. For instance, in one use-case example, the flexible componentmay be formed as a slotted spring structure. In another use-caseexample, selected walls of the cross-member may be thinned to achieve adesired amount of cross-member flexion suiting end-use design goals. Inanother use-case example, a more flexible alloy may be selected for thematerial construction of the flexible component of the cross-member whencompared to the sleeve body. Still further in other use-case examples, acombination of geometric profiling (e.g., structural wall thinning) andcross-member material construction may be jointly used to achievecompliance objectives. It will be understood, that the amount ofcross-member compliance may be selected based on design parameters suchas an expected range of speeds of the anode, expected operatingtemperature range, shaft diameter, sleeve diameter, liquid metal filmthickness, etc.

FIG. 5 shows a method 500 for operation of a hydrodynamic bearingsystem. The method 500 as well as the other control strategies describedherein may be implemented by any of the systems, assemblies, components,devices, etc., described above with regard to FIGS. 1-4. However, inother examples, the method 500 may be carried out by other suitablesystems, assemblies, components, devices, etc. Instructions for carryingout method 500 and/or the other control strategies described herein maybe at least partially executed by a processor based on instructionsstored in memory (e.g., non-transitory memory).

At 502, the method includes determining system operating conditions. Theoperating conditions may include x-ray beam intensity, x-ray beamduration, etc. Next at 504, the method includes rotating the sleeveassembly based on the system operating conditions. It will beappreciated that due to the fixed axial boundary conditions andcantilever shaft design the system may achieve a higher load carryingcapacity and increased ability to resist leaks than previous bearingdesigns.

A technical effect of providing a cross-member in a sleeve of ahydrodynamic bearing system which fluidly separates cavities housingdiscrete shafts is to increase fluid stability in the bearing system toreduce fluid leaks, during for example, handling, processing, and/or useof the system.

In another representation, an x-ray tube with a straddle liquid metalbearing assembly is provided. The straddle liquid metal bearing assemblyincludes a sleeve with an anode coupled thereto, designed to rotate, andincluding an extension fluidly isolating a first interior opening from asecond interior opening, where the first and second interior openingsenclose portions of two discrete cantilever shafts and where each of theshafts are fixedly coupled to a stationary component.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” and “the” are intended to mean thatthere are one or more of the elements. The terms “first,” “second,” andthe like, do not denote any order, quantity, or importance, but ratherare used to distinguish one element from another. The terms“comprising,” “including,” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements. As the terms “connected to,” “coupled to,” etc. are usedherein, one object (e.g., a material, element, structure, member, etc.)can be connected to or coupled to another object regardless of whetherthe one object is directly connected or coupled to the other object orwhether there are one or more intervening objects between the one objectand the other object. In addition, it should be understood thatreferences to “one embodiment” or “an embodiment” of the presentdisclosure are not intended to be interpreted as excluding the existenceof additional embodiments that also incorporate the recited features. Asdescribed herein “approximately” and “substantially” refer to values ofwithin plus or minus five percent, unless otherwise noted.

In addition to any previously indicated modification, numerous othervariations and alternative arrangements may be devised by those skilledin the art without departing from the spirit and scope of thisdescription, and appended claims are intended to cover suchmodifications and arrangements. Thus, while the information has beendescribed above with particularity and detail in connection with what ispresently deemed to be the most practical and preferred aspects, it willbe apparent to those of ordinary skill in the art that numerousmodifications, including, but not limited to, form, function, manner ofoperation and use may be made without departing from the principles andconcepts set forth herein. Also, as used herein, the examples andembodiments, in all respects, are meant to be illustrative only andshould not be construed to be limiting in any manner.

1. A hydrodynamic bearing system comprising: a sleeve assembly includinga cross-member fluidically dividing a first interior cavity from asecond interior cavity; a first shaft positioned in the first interiorcavity; a second shaft positioned in the second interior cavity; a firstjournal bearing including a first fluid interface surrounding at least aportion of the first shaft and configured to support radial loads; and asecond journal bearing including a second fluid interface surrounding atleast a portion of the second shaft and configured to support radialload, wherein the cross-member includes a flexible component configuredto accommodate for flexion between a first sleeve section including thefirst interior cavity and a second sleeve section including the secondinterior cavity.
 2. The hydrodynamic bearing system of claim 1, wherethe sleeve assembly is configured to rotate and includes an anodecoupled thereto and where the first and second shafts are stationary andare formed as cantilever shafts.
 3. (canceled)
 4. The hydrodynamicbearing system of claim 3, where the flexible component is formed from adifferent material than the first sleeve section and the second sleevesection.
 5. (canceled)
 6. The hydrodynamic bearing system of claim 1,further comprising a first thrust bearing including a first flange inthe first shaft positioned axially outward from the first journalbearing.
 7. The hydrodynamic bearing system of claim 6, furthercomprising a second thrust bearing including a second flange in thesecond shaft positioned axially outward from the second journal bearing.8. The hydrodynamic bearing system of claim 1, further comprising afirst rotating seal formed between the first shaft and the firstinterior cavity and a second rotating seal formed between the secondshaft and the second interior cavity.
 9. The hydrodynamic bearing systemof claim 1, where the first interior cavity is a first blind opening ina monolithic sleeve body and the second interior cavity is a secondblind opening in the monolithic sleeve body.
 10. The hydrodynamicbearing system of claim 1, where the cross-member includes a firstextension fluidly sealing an axial end of the first interior cavity anda second extension fluidly sealing an axial end of the second interiorcavity.
 11. The hydrodynamic bearing system of claim 10, where the firstextension is welded or press-fit into the first interior cavity and thesecond extension is welded or press-fit into the second interior cavity.12. The hydrodynamic bearing system of claim 10, where the cross-memberincludes a flexible component radially extending between the firstextension and the second extension.
 13. The hydrodynamic bearing systemof claim 12, where the sleeve assembly includes a first sleeve sectionincluding the first interior cavity coupled to a second sleeve sectionincluding the second interior cavity and the hydrodynamic bearing systemfurther comprises an anode coupled to and extending between around thefirst sleeve section and the second sleeve section.
 14. A method foroperation of a hydrodynamic bearing system, comprising: rotating asleeve assembly; where the sleeve assembly includes a cross-memberfluidically dividing a first interior cavity from a second interiorcavity; where a first shaft is positioned in the first interior cavity;where a second shaft is positioned in the second interior cavity; andwhere the hydrodynamic bearing system includes: a first journal bearingincluding a first fluid interface surrounding a portion of the firstshaft and configured to support radial loads; and a second journalbearing including a second fluid interface surrounding a portion of thesecond shaft and configured to support radial loads wherein thecross-member includes a flexible component configured to accommodate forflexion between a first sleeve section including the first interiorcavity and a second sleeve section including the second interior cavity.15. The method of claim 14, where the sleeve assembly is rotated andincludes an anode coupled thereto and where the first shaft and thesecond shaft are formed as cantilever shafts.
 16. A liquid metal bearingsystem comprising: a sleeve assembly having an anode coupled thereto andincluding a cross-member providing a fixed axial fluid boundarycondition at an axial end of each of a first interior cavity and asecond interior cavity; a first cantilever shaft positioned in the firstinterior cavity; a second cantilever shaft positioned in the secondinterior cavity; a first journal bearing including a first fluidinterface between the first cantilever shaft and the first interiorcavity; a second journal bearing including a second fluid interfacebetween the second cantilever shaft and the second interior cavity; anda first thrust bearing including a first flange in the first cantilevershaft.
 17. The liquid metal bearing system of clam 16, furthercomprising a second thrust bearing including a second flange in thesecond cantilever shaft.
 18. The liquid metal bearing system of claim17, further comprising a first rotating seal formed between the firstcantilever shaft and the first interior cavity and positioned axiallyoutward from the first journal bearing and the first thrust bearing anda second rotating seal formed between the second cantilever shaft andthe second interior cavity and positioned axially outward from thesecond journal bearing and the second thrust bearing.
 19. The liquidmetal bearing system of claim 16, where the cross-member includes aflexible component having less bending stiffness than a first sleevesection including the first interior cavity and a second sleeve sectionincluding the second interior cavity.
 20. The liquid metal bearingsystem of claim 19, where the anode circumferentially surrounds theflexible component.